1. Field of the Invention
This invention relates to a mount structure for a double ended lamp having improved resistance to breaking under impact stress. More particularly, this invention relates to supporting a longitudinally aligned double ended lamp in a reflector by means of a long and short mount wire welded to respective ones of the two lamp inlead wires, wherein the cross section of the short wire is smaller than that of the long wire, but not smaller than that of the lamp inlead wire and wherein the lamp inlead wire welded to the short mount wire is molybdenum which has been alloyed to have a recrystallization temperature at least about 200.degree. C. higher than molybdenum wire without such alloying.
2. Background of the Disclosure
Double ended lamps comprising a generally tubular vitreous envelope enclosing either a filament or electrodes within and being hermetically sealed at both ends are well known to those skilled in the art.
Such lamps include filament-halogen lamps which are generally made of a quartz tube enclosing a tungsten filament within a filament chamber and hermetically sealed on both ends by means of a pinch or shrink seal over a molybdenum foil seal assembly. One or more halogens are sealed within the filament chamber whose surface may or may not contain a coating or filter which transmits and/or reflects selective portions of light radiation emitted by the filament. Also included are arc lamps wherein the quartz tube contains two electrodes hermetically sealed within an arc chamber which also contains one or more metal halides. Such lamps are able to produce considerably more light output than ordinary incandescent lamps and are particularly useful in relatively small sizes enclosed in reflector assemblies for use in general indoor, outdoor and automotive lighting.
These lamps, when mounted in lamp reflectors, have exhibited problems of breakage when subjected to impact stresses during shipping and in automotive applications, particularly when the longitudinal axis of the lamp is aligned with the longitudinal axis of the reflector so that a long and short mount wire must be employed within the reflector assembly in order to secure the lamp. The outer lead wires of these lamps are made of molybdenum for various reasons. The mount wires used to secure the lamp are welded to the molybdenum lamp outer lead wires protruding outwardly from each end of the lamp by known means such as arc welding, laser welding, resistance welding, etc. The welding operation results in localized stresses and recrystallization of the molybdenum lamp lead wires at the point of welding. Recrystallization of the molybdenum wire has been found to result in increased breaking of the outer lamp lead just above the point at which it is welded to the shorter mount wire.